In season 2 episode 9 "The Ex Factor" Sandy, Kirsten, Alex and Marissa are seen kicking back watching a spooky movie (in their separate houses). The movie that is being broadcast-ed (apparently the only movie channel in THE O.C.) is the 1959 smash hit "House On Haunted Hill".
The funny thing about this whole situation is that Marissa refers to Caleb and her mother Julie's house as "The House On Haunted Hill" in season 1 episode 27 "The Ties That Bind".
In Season 2 episode 2 Marissa and Ryan hang out at her new house. First dialog spoken by Marissa is: "So there it is, the haunted mansion.".
What makes this whole thing even more funny is the fact that Peter Gallagher aka Sandy Cohen starred in the 1999 remake of the film.
And Lastly to put a cherry on this whole haunted sundae, Amanda Righetti Aka Kirstens little delinquent sister Hailey Nichol, plays in the 2007 remake "Return to House on Haunted Hill". SPOOOKY!!